Plant small RNAs (sRNAs) play significant roles in regulating various developmental processes and hormone signalling pathways involved in plant responses to a wide range of biotic and abiotic stresses. However, the functions of sRNAs in response to rice sheath blight remain unclear. We screened rice (Oryza sativa) sRNA expression patterns against Rhizoctonia solani and found that Tourist-miniature inverted-repeat transposable element (MITE)-derived small interfering RNA (siRNA) (here referred to as siR109944) expression was clearly suppressed upon R. solani infection. One potential target of siR109944 is the F-Box domain and LRR-containing protein 55 (FBL55), which encode the transport inhibitor response 1 (TIR1)-like protein. We found that rice had significantly enhanced susceptibility when siR109944 was overexpressed, while FBL55 OE plants showed resistance to R. solani challenge. Additionally, multiple agronomic traits of rice, including root length and flag leaf inclination, were affected by siR109944 expression. Auxin metabolism-related and signalling pathway-related genes were differentially expressed in the siR109944 OE and FBL55 OE plants. Importantly, pre-treatment with auxin enhanced sheath blight resistance by affecting endogenous auxin homeostasis in rice. Furthermore, transgenic Arabidopsis overexpressing siR109944 exhibited early flowering, increased tiller numbers, and increased susceptibility to R. solani. Our results demonstrate that siR109944 has a conserved function in interfering with plant immunity, growth, and development by affecting auxin homeostasis in planta. Thus, siR109944 provides a genetic target for plant breeding in the future. Furthermore, exogenous application of indole-3-acetic acid (IAA) or auxin analogues might effectively protect field crops against diseases.

中文翻译：

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水稻siR109944通过影响植物生长素的稳态来抑制植物对白叶枯病的免疫力并影响多种农艺性状。

植物小RNA（sRNA）在调节植物对多种生物和非生物胁迫的反应所涉及的各种发育过程和激素信号传导途径中起着重要作用。但是，尚不清楚sRNA对水稻鞘枯病的反应功能。我们筛选了针对茄枯萎病菌的水稻（Oryza sativa）sRNA表达模式，发现在R. solani上明显抑制了游客微型反向重复转座因子（MITE）衍生的小干扰RNA（siRNA）（siRNA）的表达。感染。siR109944的一个潜在靶标是F-Box结构域和含LRR的蛋白55（FBL55），它们编码转运抑制剂应答1（TIR1）样蛋白。我们发现当siR109944过表达时，水稻的敏感性大大提高，而FBL55 OE植物表现出对solani挑战的抗性。此外，siR109944表达影响了水稻的多种农艺性状，包括根长和旗叶倾角。生长素代谢相关基因和信号通路相关基因在siR109944 OE和FBL55 OE植物中差异表达。重要的是，用生长素进行预处理会影响水稻的内源性生长素稳态，从而增强了抗白叶枯病的能力。此外，过表达siR109944的转基因拟南芥表现出早期开花，分till数量增加和对茄状梭菌的敏感性增加。我们的结果表明，siR109944具有保守功能，可通过影响植物体内植物生长素的稳态来干扰植物的免疫，生长和发育。因此，siR109944为将来的植物育种提供了遗传靶标。